Suchergebnisse

Abstract
A planer equipped with a rotating cutting drum is used to remove about ten cm thick of road surfaces. This process generates dust likely to contain crystalline silica. The machine operator and people around may be particularly exposed. It is therefore essential to promote effective preventive solutions, in particular from dust collection and filtration systems, to reduce dust exposure. Tests were realized to evaluate the performance of technical devices designed to capture and filter dust emitted by road planers. The measurements were carried out on a road planer equipped with an air collection device located next to the milling drum, supplemented by an electrostatic separator to trap collected dust. The dust collection efficiency of the venting system was determined by gas tracing. The efficiency of the electrostatic separator was both evaluated in laboratory conditions (static machine) from a reference dust generated upstream of the system, and in the field during road surface planing. The tests conducted on the planer showed the effectiveness of the dust collection and filtration devices implanted on the machine and tested both in static and in the field. The capture efficiency determined by gas tracing is about 90 % and the separation efficiency of the electrostatic precipitator, determined on the static machine from test dust, is respectively 60 and 90% at aerodynamic diameters 1 and 4 μm. The average separation efficiency obtained from the measurements with the machine in real operation is 91% for respirable dust and 95% for respirable crystalline silica.

Abstract
A large-scale measurement campaign (9 days, more than 400 measurements) was conducted to characterise the exposure of cheese workers involved in maturing and packaging. Airborne microbial and chemical agents were measured in a company producing different types of cheeses. Several air pollutants were investigated (culturable microorganisms, total particles, carbon dioxide, ammonia, VOCs etc.) by mean of ambient and personal measurements. A massive emission of particles into the air was found for tasks involving the brushing of a category of cheeses, with significant personal exposures to culturable fungi (up to 108 CFU/m3_filter cassettes_2L/min). Dominant fungi belonged to Penicillium species with allergenic potential. Ripening rooms can contain high concentrations of carbon dioxide and several tasks performed in them have shown high individual exposures levels (instantaneous concentration up to 10 000 ppmv_ToxiRAE Pro CO2 portable detector). High relative air humidity (> 95%) was also found in the ripening rooms. Real-time measurement of airborne particles (FIDAS Frog particle counter) and gases (FTIR Gasmet™ gas analyser) allowed the identification of events (ventilation, door opening, etc.) that could affect pollutant concentrations and flows. The observed exposure of cheese worker to funig represents an immuno-allergic risk and their exposure to carbon dioxide appeals attention. The multiple nature of exposure raises questions about the technical and organisational mitigation strategies to implement. The multi-exposure measurement strategy deployed in the company proved to be relevant and allowed for a more comprehensive risk assessment. It provided valuable information for formulating prevention recommendations appropriate to the situation. A study including several cheese companies is in course.